From the Guidelines
For patients with antiphospholipid syndrome, the goal INR rate with warfarin should be between 2 and 3 to effectively balance the risk of excessive bleeding against the risk of thrombosis. This recommendation is based on the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack from the American Heart Association/American Stroke Association 1. The guideline suggests that in patients with ischemic stroke or TIA with confirmed antiphospholipid syndrome treated with warfarin, a target INR between 2 and 3 is reasonable to reduce the risk of recurrent stroke or TIA while minimizing bleeding risks.
Some key points to consider when managing antiphospholipid syndrome patients on warfarin include:
- Antiplatelet therapy alone is recommended for patients with isolated antiphospholipid antibody but do not fulfill the criteria for antiphospholipid syndrome 1
- Warfarin is recommended for patients with ischemic stroke or TIA who meet the criteria for antiphospholipid syndrome to reduce the risk of recurrent stroke or TIA 1
- Rivaroxaban is not recommended for patients with antiphospholipid syndrome with history of thrombosis and triple-positive antiphospholipid antibodies due to excess thrombotic events compared with warfarin 1
Regular INR monitoring is essential to ensure that patients remain within the target range, and warfarin dosing should be adjusted gradually based on frequent INR monitoring, especially during initiation. Patients should maintain consistent vitamin K intake through diet to avoid INR fluctuations and should be educated about potential drug interactions that can affect warfarin metabolism. By targeting an INR range of 2-3, healthcare providers can help minimize the risk of thrombotic events while reducing bleeding risks in patients with antiphospholipid syndrome.
From the FDA Drug Label
For patients with a first episode of DVT or PE who have documented antiphospholipid antibodies or who have two or more thrombophilic conditions, treatment for 12 months is recommended and indefinite therapy is suggested The dose of warfarin should be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations.
The goal INR rate with warfarin for antiphospholipid syndrome patients is 2.5 (range, 2.0 to 3.0) 2.
From the Research
Goal INR Rate with Warfarin in Antiphospholipid Syndrome Patients
- The recommended INR range for patients with antiphospholipid syndrome (APS) and a first venous thromboembolic event is 2.0 to 3.0 3.
- Higher anticoagulation intensity, with an INR range of 3.0 to 4.0, is recommended for patients presenting with arterial events 3.
- Moderate-intensity warfarin, with a target INR of 2.0-3.0, reduces the risk of recurrent venous thrombosis by 80% to 90% in patients with APS 4.
- There is no evidence that high-intensity warfarin (target INR, >3.0) is more effective than moderate-intensity warfarin in preventing recurrent thrombosis in APS patients 5, 4.
- The use of point-of-care testing to monitor INR in APS patients may be acceptable, but requires further study due to potential interactions between antiphospholipid antibodies and thromboplastin used for INR testing 6.
Specific Considerations
- Patients with APS and a history of venous thrombosis who have discontinued anticoagulant drugs within 6 months are at high risk of recurrent thrombosis (>10% in the first year) 4.
- Aspirin and moderate-intensity warfarin appear equally effective for preventing recurrent stroke in patients with prior stroke and a single positive test result for antiphospholipid antibody 4.
- The optimal treatment of noncerebrovascular arterial thrombosis, recurrent thrombosis despite warfarin therapy, and treatment of women with antiphospholipid antibodies and recurrent fetal loss requires further study 4.